git-diff(1) Manual Page

NAME

SYNOPSIS

DESCRIPTION

Show changes between two trees, a tree and the working tree, a
tree and the index file, or the index file and the working tree.

git diff [--options] [--] [<path>…]

This form is to view the changes you made relative to
the index (staging area for the next commit). In other
words, the differences are what you could tell git to
further add to the index but you still haven’t. You can
stage these changes by using git-add(1).

If exactly two paths are given, and at least one is untracked,
compare the two files / directories. This behavior can be
forced by --no-index.

git diff [--options] --cached [<commit>] [--] [<path>…]

This form is to view the changes you staged for the next
commit relative to the named <commit>. Typically you
would want comparison with the latest commit, so if you
do not give <commit>, it defaults to HEAD.
--staged is a synonym of --cached.

git diff [--options] <commit> [--] [<path>…]

This form is to view the changes you have in your
working tree relative to the named <commit>. You can
use HEAD to compare it with the latest commit, or a
branch name to compare with the tip of a different
branch.

git diff [--options] <commit> <commit> [--] [<path>…]

This is to view the changes between two arbitrary
<commit>.

git diff [--options] <commit>..<commit> [--] [<path>…]

This is synonymous to the previous form. If <commit> on
one side is omitted, it will have the same effect as
using HEAD instead.

git diff [--options] <commit>...<commit> [--] [<path>…]

This form is to view the changes on the branch containing
and up to the second <commit>, starting at a common ancestor
of both <commit>. "git diff A...B" is equivalent to
"git diff $(git-merge-base A B) B". You can omit any one
of <commit>, which has the same effect as using HEAD instead.

Just in case if you are doing something exotic, it should be
noted that all of the <commit> in the above description, except
for the last two forms that use ".." notations, can be any
<tree-ish>.

For a more complete list of ways to spell <commit>, see
"SPECIFYING REVISIONS" section in git-rev-parse(1).
However, "diff" is about comparing two endpoints, not ranges,
and the range notations ("<commit>..<commit>" and
"<commit>...<commit>") do not mean a range as defined in the
"SPECIFYING RANGES" section in git-rev-parse(1).

OPTIONS

-p

-u

Generate patch (see section on generating patches).
This is the default.

Generate a diffstat. You can override the default
output width for 80-column terminal by --stat=width.
The width of the filename part can be controlled by
giving another width to it separated by a comma.

--numstat

Similar to \--stat, but shows number of added and
deleted lines in decimal notation and pathname without
abbreviation, to make it more machine friendly. For
binary files, outputs two - instead of saying
0 0.

--shortstat

Output only the last line of the --stat format containing total
number of modified files, as well as number of added and deleted
lines.

--dirstat[=limit]

Output the distribution of relative amount of changes (number of lines added or
removed) for each sub-directory. Directories with changes below
a cut-off percent (3% by default) are not shown. The cut-off percent
can be set with --dirstat=limit. Changes in a child directory is not
counted for the parent directory, unless --cumulative is used.

--dirstat-by-file[=limit]

Same as --dirstat, but counts changed files instead of lines.

--summary

Output a condensed summary of extended header information
such as creations, renames and mode changes.

--patch-with-stat

Synonym for -p --stat.

-z

When --raw, --numstat, --name-only or --name-status has been
given, do not munge pathnames and use NULs as output field terminators.

Without this option, each pathname output will have TAB, LF, double quotes,
and backslash characters replaced with \t, \n, \", and \\,
respectively, and the pathname will be enclosed in double quotes if
any of those replacements occurred.

--name-only

Show only names of changed files.

--name-status

Show only names and status of changed files. See the description
of the --diff-filter option on what the status letters mean.

--submodule[=<format>]

Chose the output format for submodule differences. <format> can be one of
short and log. short just shows pairs of commit names, this format
is used when this option is not given. log is the default value for this
option and lists the commits in that commit range like the summary
option of git-submodule(1) does.

--color[=<when>]

Show colored diff.
The value must be always (the default), never, or auto.

--no-color

Turn off colored diff, even when the configuration file
gives the default to color output.
Same as --color=never.

--color-words[=<regex>]

Show colored word diff, i.e., color words which have changed.
By default, words are separated by whitespace.

When a <regex> is specified, every non-overlapping match of the
<regex> is considered a word. Anything between these matches is
considered whitespace and ignored(!) for the purposes of finding
differences. You may want to append |[^[:space:]] to your regular
expression to make sure that it matches all non-whitespace characters.
A match that contains a newline is silently truncated(!) at the
newline.

The regex can also be set via a diff driver or configuration option, see
gitattributes(1) or git-config(1). Giving it explicitly
overrides any diff driver or configuration setting. Diff drivers
override configuration settings.

--no-renames

Turn off rename detection, even when the configuration
file gives the default to do so.

--check

Warn if changes introduce trailing whitespace
or an indent that uses a space before a tab. Exits with
non-zero status if problems are found. Not compatible with
--exit-code.

--full-index

Instead of the first handful of characters, show the full
pre- and post-image blob object names on the "index"
line when generating patch format output.

--binary

In addition to --full-index, output a binary diff that
can be applied with git-apply.

--abbrev[=<n>]

Instead of showing the full 40-byte hexadecimal object
name in diff-raw format output and diff-tree header
lines, show only a partial prefix. This is
independent of the --full-index option above, which controls
the diff-patch output format. Non default number of
digits can be specified with --abbrev=<n>.

-B

Break complete rewrite changes into pairs of delete and create.

-M

Detect renames.

-C

Detect copies as well as renames. See also --find-copies-harder.

--diff-filter=[ACDMRTUXB*]

Select only files that are Added (A), Copied (C),
Deleted (D), Modified (M), Renamed (R), have their
type (i.e. regular file, symlink, submodule, …) changed (T),
are Unmerged (U), are
Unknown (X), or have had their pairing Broken (B).
Any combination of the filter characters may be used.
When * (All-or-none) is added to the combination, all
paths are selected if there is any file that matches
other criteria in the comparison; if there is no file
that matches other criteria, nothing is selected.

--find-copies-harder

For performance reasons, by default, -C option finds copies only
if the original file of the copy was modified in the same
changeset. This flag makes the command
inspect unmodified files as candidates for the source of
copy. This is a very expensive operation for large
projects, so use it with caution. Giving more than one
-C option has the same effect.

-l<num>

The -M and -C options require O(n^2) processing time where n
is the number of potential rename/copy targets. This
option prevents rename/copy detection from running if
the number of rename/copy targets exceeds the specified
number.

-S<string>

Look for differences that introduce or remove an instance of
<string>. Note that this is different than the string simply
appearing in diff output; see the pickaxe entry in
gitdiffcore(7) for more details.

--pickaxe-all

When -S finds a change, show all the changes in that
changeset, not just the files that contain the change
in <string>.

--pickaxe-regex

Make the <string> not a plain string but an extended POSIX
regex to match.

-O<orderfile>

Output the patch in the order specified in the
<orderfile>, which has one shell glob pattern per line.

-R

Swap two inputs; that is, show differences from index or
on-disk file to tree contents.

--relative[=<path>]

When run from a subdirectory of the project, it can be
told to exclude changes outside the directory and show
pathnames relative to it with this option. When you are
not in a subdirectory (e.g. in a bare repository), you
can name which subdirectory to make the output relative
to by giving a <path> as an argument.

-a

--text

Treat all files as text.

--ignore-space-at-eol

Ignore changes in whitespace at EOL.

-b

--ignore-space-change

Ignore changes in amount of whitespace. This ignores whitespace
at line end, and considers all other sequences of one or
more whitespace characters to be equivalent.

-w

--ignore-all-space

Ignore whitespace when comparing lines. This ignores
differences even if one line has whitespace where the other
line has none.

--inter-hunk-context=<lines>

Show the context between diff hunks, up to the specified number
of lines, thereby fusing hunks that are close to each other.

--exit-code

Make the program exit with codes similar to diff(1).
That is, it exits with 1 if there were differences and
0 means no differences.

--quiet

Disable all output of the program. Implies --exit-code.

--ext-diff

Allow an external diff helper to be executed. If you set an
external diff driver with gitattributes(5), you need
to use this option with git-log(1) and friends.

--no-ext-diff

Disallow external diff drivers.

--ignore-submodules

Ignore changes to submodules in the diff generation.

--src-prefix=<prefix>

Show the given source prefix instead of "a/".

--dst-prefix=<prefix>

Show the given destination prefix instead of "b/".

--no-prefix

Do not show any source or destination prefix.

For more detailed explanation on these common options, see also
gitdiffcore(7).

<path>…

The <paths> parameters, when given, are used to limit
the diff to the named paths (you can give directory
names and get diff for all files under them).

Raw output format

The raw output format from "git-diff-index", "git-diff-tree",
"git-diff-files" and "git diff --raw" are very similar.

These commands all compare two sets of things; what is
compared differs:

git-diff-index <tree-ish>

compares the <tree-ish> and the files on the filesystem.

git-diff-index --cached <tree-ish>

compares the <tree-ish> and the index.

git-diff-tree [-r] <tree-ish-1> <tree-ish-2> [<pattern>…]

compares the trees named by the two arguments.

git-diff-files [<pattern>…]

compares the index and the files on the filesystem.

The "git-diff-tree" command begins its output by printing the hash of
what is being compared. After that, all the commands print one output
line per changed file.

U: file is unmerged (you must complete the merge before it can
be committed)

X: "unknown" change type (most probably a bug, please report it)

Status letters C and R are always followed by a score (denoting the
percentage of similarity between the source and target of the move or
copy), and are the only ones to be so.

<sha1> is shown as all 0’s if a file is new on the filesystem
and it is out of sync with the index.

Example:

:100644 100644 5be4a4...... 000000...... M file.c

When -z option is not used, TAB, LF, and backslash characters
in pathnames are represented as \t, \n, and \\,
respectively.

diff format for merges

"git-diff-tree", "git-diff-files" and "git-diff --raw"
can take -c or --cc option
to generate diff output also for merge commits. The output differs
from the format described above in the following way:

there is a colon for each parent

there are more "src" modes and "src" sha1

status is concatenated status characters for each parent

no optional "score" number

single path, only for "dst"

Example:

::100644 100644 100644 fabadb8... cc95eb0... 4866510... MM describe.c

Note that combined diff lists only files which were modified from
all parents.

Generating patches with -p

When "git-diff-index", "git-diff-tree", or "git-diff-files" are run
with a -p option, "git diff" without the --raw option, or
"git log" with the "-p" option, they
do not produce the output described above; instead they produce a
patch file. You can customize the creation of such patches via the
GIT_EXTERNAL_DIFF and the GIT_DIFF_OPTS environment variables.

What the -p option produces is slightly different from the traditional
diff format.

It is preceded with a "git diff" header, that looks like
this:

diff --git a/file1 b/file2

The a/ and b/ filenames are the same unless rename/copy is
involved. Especially, even for a creation or a deletion,
/dev/null is not used in place of a/ or b/ filenames.

When rename/copy is involved, file1 and file2 show the
name of the source file of the rename/copy and the name of
the file that rename/copy produces, respectively.

TAB, LF, double quote and backslash characters in pathnames
are represented as \t, \n, \" and \\, respectively.
If there is need for such substitution then the whole
pathname is put in double quotes.

The similarity index is the percentage of unchanged lines, and
the dissimilarity index is the percentage of changed lines. It
is a rounded down integer, followed by a percent sign. The
similarity index value of 100% is thus reserved for two equal
files, while 100% dissimilarity means that no line from the old
file made it into the new one.

combined diff format

"git-diff-tree", "git-diff-files" and "git-diff" can take -c or
--cc option to produce combined diff. For showing a merge commit
with "git log -p", this is the default format; you can force showing
full diff with the -m option.
A combined diff format looks like this:

The mode <mode>,<mode>..<mode> line appears only if at least one of
the <mode> is different from the rest. Extended headers with
information about detected contents movement (renames and
copying detection) are designed to work with diff of two
<tree-ish> and are not used by combined diff format.

It is followed by two-line from-file/to-file header

--- a/file
+++ b/file

Similar to two-line header for traditional unified diff
format, /dev/null is used to signal created or deleted
files.

Chunk header format is modified to prevent people from
accidentally feeding it to patch -p1. Combined diff format
was created for review of merge commit changes, and was not
meant for apply. The change is similar to the change in the
extended index header:

@@@ <from-file-range> <from-file-range> <to-file-range> @@@

There are (number of parents + 1) @ characters in the chunk
header for combined diff format.

Unlike the traditional unified diff format, which shows two
files A and B with a single column that has - (minus — appears in A but removed in B), + (plus — missing in A but
added to B), or " " (space — unchanged) prefix, this format
compares two or more files file1, file2,… with one file X, and
shows how X differs from each of fileN. One column for each of
fileN is prepended to the output line to note how X’s line is
different from it.

A - character in the column N means that the line appears in
fileN but it does not appear in the result. A + character
in the column N means that the line appears in the result,
and fileN does not have that line (in other words, the line was
added, from the point of view of that parent).

In the above example output, the function signature was changed
from both files (hence two - removals from both file1 and
file2, plus ++ to mean one line that was added does not appear
in either file1 nor file2). Also eight other lines are the same
from file1 but do not appear in file2 (hence prefixed with {plus}).

When shown by git diff-tree -c, it compares the parents of a
merge commit with the merge result (i.e. file1..fileN are the
parents). When shown by git diff-files -c, it compares the
two unresolved merge parents with the working tree file
(i.e. file1 is stage 2 aka "our version", file2 is stage 3 aka
"their version").

other diff formats

The --summary option describes newly added, deleted, renamed and
copied files. The --stat option adds diffstat(1) graph to the
output. These options can be combined with other options, such as
-p, and are meant for human consumption.

When showing a change that involves a rename or a copy, --stat output
formats the pathnames compactly by combining common prefix and suffix of
the pathnames. For example, a change that moves arch/i386/Makefile to
arch/x86/Makefile while modifying 4 lines will be shown like this:

arch/{i386 => x86}/Makefile | 4 +--

The --numstat option gives the diffstat(1) information but is designed
for easier machine consumption. An entry in --numstat output looks
like this:

1 2 README
3 1 arch/{i386 => x86}/Makefile

That is, from left to right:

the number of added lines;

a tab;

the number of deleted lines;

a tab;

pathname (possibly with rename/copy information);

a newline.

When -z output option is in effect, the output is formatted this way:

1 2 README NUL
3 1 NUL arch/i386/Makefile NUL arch/x86/Makefile NUL

That is:

the number of added lines;

a tab;

the number of deleted lines;

a tab;

a NUL (only exists if renamed/copied);

pathname in preimage;

a NUL (only exists if renamed/copied);

pathname in postimage (only exists if renamed/copied);

a NUL.

The extra NUL before the preimage path in renamed case is to allow
scripts that read the output to tell if the current record being read is
a single-path record or a rename/copy record without reading ahead.
After reading added and deleted lines, reading up to NUL would yield
the pathname, but if that is NUL, the record will show two paths.

EXAMPLES

Various ways to check your working tree

$ git diff <1>
$ git diff --cached <2>
$ git diff HEAD <3>

Changes in the working tree not yet staged for the next commit.

Changes between the index and your last commit; what you
would be committing if you run "git commit" without "-a" option.

Changes in the working tree since your last commit; what you
would be committing if you run "git commit -a"